Manufacture of large-grained dextrose



Patented Aug. 30, 1927.

UNITED STATES 1,640,717 PATENT OFFICE.

WILLIAM' B. NEWKIRK, OF RIVERSIDE, ILLINOIS, -ASSIGNOR 'IO INTERNATIONAL PATENTS DEVELOPMENT COMPANY, OF WILMINGTON, DELAWARE, A CORPORA- TION OF DELAWARE.

muurac'runa' or LABGE-GRAINED nnx'rnosn.

. no Drawing. Original application filed September 10, 1924, Serial N... 730345; Divided and this application filed October 23, 1924. Serial No. 745,375.

My invention relates to the manufacture of dextrose from starch or starch bearing materials and its object is to provide a novel method of making a pure or substantially pure dextrose in the form of large grams or crystals. This application is a d1v1s1on of my co-pending application Serial No. 736,-

945 (Patent No. 1,521,830), filed Se tember- 10, 1924 as a continuation in part an application Serial No. 705,780, filed April 11, 1924.

The dextrose of the type contemplated by thisinvention may be-either of the hydrate or the anhydrous type.

The preferred method of manufacturlng the hydrate is as follows:

The starch is converted, preferably by the usual method of hydrolysis toas high a dextrose content as practical, 89% to 90% for example, based on dry substances. The converted-liquor is then preferably filtered by being run through bone char and 1s thereafter concentrated in a vacuum pan to a density of from approximately 88 to 40 Baum. The prefera 1y density 1s close to 38 Ba-uni. This density is considerably lower than the preferred density em loyed for making the smaller grained pro uct 1n accordance with the process described in application, Serial No. 736,945. The concentration in the vacuum pan may be conducted according to circumstances at any temperature 'from 130 t(y180- Fahrenheit. The

liquor taken from the vacuum pan is then preferably cooled and thereafter is introduced into a crystallizer'which latter is provided preferably with means for keeping the solution in gentle agitation and with cooling means such, ,for example, as a water jacket. The liquor is referably cooled, precedent to being intro uced into the crystallizer sufficiently, to give it substantial supersaturation without however inducing the formation of crystals to any appreciable extent. This is possible because of the large supersaturation which dextrose solutions can carry. After the solution hasbeen cooled it is mixed with a relatively large quantity of dextrose in the solid phase (crystals); For this purpose I use, pre erably, a ortion of the crystallized magma (crysta s and mother liquor termed foots) from a preceding crystallizing operation, this portion of the batch being 18a. in the-crystallize!" and. the fresh liquor being run upon the same before the footshave had a chance to set.

purity of the converted liquid! of about i 89%), the other of the batch oonsistin of fresh converted, concentrated and coole solution. These proportions maybe varied over quite a Wide range. The amount of foots may for example, vary from 30% to 45% of the batch with a liquor of approximately the purity mentioned. The solid phase will ordinarily be from four-tenths to six-tenths of the foots, the remainder being mother liquor. The proportions of solid phase to liquid may therefore vary approximately from 10 to 40 parts of solids to 100 parts ofliquid. However these roportions are subject vto still further variation with converted liquors of substantially differentpurity from that mentioned. The extent to which the solution is re-cooled depends upon the temperature 0 the foots to be added thereto, the object being to regulate these temperatures so as to obtain a temperature of the mixture most favorable-for the initiation of crystallization. For the hydrate sugar this temperature is referably 105 Fahrenheit or thereabout. t may bebo11- siderably higher than this, for example as high'as 130 Fahrenheit, depending upon the character of the converted liquor .as to the quantity and nature of its impurities. While as high a temperature as 130 is withthe anhydrous range, as ordinarily considered, the predominance of the large quantity of hydrate solid phase prevents crystallization either as anhydrid-or as false grain.

If the heat developed b crystallization -(dextrose crystallizing'exot ermically) is in excess of radiation, the mass may be cooled to maintain the desired temperatureiby circulating water through the water jacket of er cooled so to bring the ultimate temto the relatively low density of the solution. However, as the orginal crystals build up in the successive batch treatments, the

quantity of newly induced crystals will in-' crease, generally speaking, in proportion to the growth in size of the old crystals until a balanced condition is arrived at; after which the old crystals will cease to row very appreciably and new crystals wil be induced in sufiicient quantity so that the process can be carried on indefinitely by the successive crystallizing operations mentioned, a part of each batch being used for seeding the following batch, the remainder being withdrawn. This withdrawn portion, approximately 60% of the batch, is centri fuged to extract the mother liquor and is then washed with water preferably, and dried. It will contain, necessaril some small grains which, if desired, may e sifted out.

The use of solid phase, as seed, in quantity suflicient so that the solid phase is what I have termed a significant factor in controlling crystallization and the derivation of this seed from a preceding crystallizing operation in the form of nascent crystals mixed with mother liquor, make it possible to obtain a purgeable magma, in which the crystals are of more than usual size and uncontaminated by false grain. The-use of relatively large quantity of foots has, in fact, a direct bearing upon the production of a large grained sugar. That is, the low gravity of the solution-involves, at normal temperatures, so slight a supersaturation,

that with a large quantity of the solid phase present in dispersed condition throughout the solution (this dispersion being accomplished, by the agitating means above referred to) most of the available sugar crystallizing out of the solution will go to build up the original seed as stated, whereas if the usual small quantity of seed were used in the first instance there would be necessarily such large induction of new crystals as to defeat the object in view.

For the manufacture of anhydrous sugar the same conditions are maintained, except that the initial temperature of crystallization will be approximately from 130 to 145 Fahrenheit for converted liquor of the ordinary purity mentioned and the. final temcessive batches and introducin perature approximately from 100 to 120 of crystals as described in my application Serial No. 736,945. a

The actual temperatures and densities will, in any case, depend, necessarily, upon the character of the converted liquor in respect'to the quantity and nature of its impurities. The duration of the crystallizing operation will also vary, considerably, depending upon the character of the material treated. The proportion as between the foots and the liquor for a given batch will also depend upon similar varying conditions. In matters of detail, therefore, something must be left to the discretion of the skilled operator.v I have endeavored to lay down the principles covering the improved rocess herein described and claimed an have stated temperatures, densities and proportions within the limits which I have found practical and desirable in order to obtain the best results from the viewpoint of high purity of the product and economy of manufacture. The term starch converteddextrose solution is intended to include not only the liquors direct from the converters, but. also mother liquors froin the centrifugals and remelts, or mixtures of any of these liquors so far as the same are suitable for the purpose of my invention.

I claim:

1. Method of making large grained crys-' talline dextrose from a starch converted solution which consists in maintaining a relatively large quantity of dextrose crystals uniformly dispersed through a solution and gradually cooling the solution to maintain a supersaturation so slight that most of the dextrose crystallizin out of the solution goes to build up the slze of the crystals originally introduced.

2. Method of making large grained crystalline dextrose from a starch converted solution which consists in introducing a relatively large quantity of dextrose crystals into and maintaining the same uniformly dispersed throu h a solution having a density of substantially 38 to 40 Baum.

3. Method of making large grained crystalline dextrose from a starch converted solution which consists in crystallizing in sucin each case to and maintaining the same uniformly dispersed through a solution having a supersaturation so slight that a large portion of the dextrose crystallizing out of the solution goes to build up the size of the introduced crystals while the remaining portion is in the form of newly induced cr stals to provide for the continuation of t e process.

4. Method of making large grained crystalline dextrose from a starch converted solution which consists in crystallizing in successive batches solutions which have a density of so. itantially 38 to 40 Baurn and introducing into and maintaining umformly dispersed through each batch of solution a quantity of foots taken from a preceding batch in amount not substantially less than 30% of the new batch.

5. Method of making large grained crystalline dextrose from a starch converted solution which consists in concentrating the solution by heating to a density of substantially 38 to 40 Baum, cooling the solution and mixing with the same a quantity of foots taken from a previous crystallizing operation in amount sufficient so that the quantity of the solid phase introduced is a significant factor in controlling-crystallization and so thatmost of the dextrose crystallizing out of the solution builds up the solid phase present instead of forming new crystals.

6. Method of making large grained crystalline dextrose. from a starch converted solution which consists in concentrating the solution by heating to-a density of substantially 38 to 40 Baum, cooling the solution,

mixing with the same a quantity of foots taken from a previous crystallizmg operation in amount sufficient so that the quantity of the. solid phase introduced is a significant 'factor in controlling crystallization and so that most of the dextrose crystallizing out of the solution builds up the solid phase present instead of forming new crystals and reducing the temperature of the magma during the crystallizing operation.

7. Method of making large grained crystalline dextrose from a starch converted. dextrose solution which consists in main taining a relatively large quantityof dextrose crystals of a, single crystal type uniformly dispersed through a dextrose solution at a temperature favorable to the crystallization of dextrose of the crystal type of the solid phase present and gradually cooling the solution to maintain a su ersaturation so slight that most of the 'extrose crystallizing out of solution goes to build up the size of the crystals originally introduced.

\VILLIAM B. NEWKIRK. 

